Structural Engineering in a Microscale Laser Diode with InGaN Tunnel-Junction Nanorods

The development of next-generation pixels with a smaller size, lower power consumption, and higher luminance is required for VR and XR display applications. Here, we showed the selective area epitaxial growth of a novel GaN nanorod-based LD tunnel-junction structure incorporating a photonic crystal effect. The nanorod based DBR-free GaN LD structure with the photonic crystal effect has demonstrated to be a surface-emitting laser diode that emits light in a vertical direction. The fabricated GaN nanorod laser diode device showed lasing performance at a wavelength of 502 nm with a full width at half-maximum of 0.98 nm. Moreover, a low turn-on voltage of ∼2.49 V was achieved by the novel tunnel junction-based n-GaN to metal contact structure, and as a result, the reduction in the light efficiency was significantly improved, even during a long operating time. Such a unique 5 μm × 5 μm nanorod LD device is not only useful for future display pixels that need to have high brightness and ultrahigh definition, but also opens up a new platform of nano-optoelectronic devices in the future.